70 



surface, when it gradually curves until this surface is nearly met. This 

 last portion forms the pupal cell, and is wholly unlike the exit chamber 

 of any other borer that the writer has seen on chestnut. 



Later in the month, when the observations were made in the vicinity 

 of Washington, the writer was in charge of the exhibit of the Division 

 of Entomology at the Columbian Exposition. During his stay there 

 Mr. J. S. Eaymond brought in two large specimens of the work of what 

 was undoubtedly the same insect in oak, with the report that damage 

 of this nature was quite extensive in northern Illinois. The infested 

 specimens were from Mr. H. E. Hamilton, Eichmoud, 111., where they 

 were attacking oaks growing thickly together on a lawn. Similarly 

 affected trees were noticed at the same time by Mr. G. B. Sud worth, of 

 this Department, in the neighborhood of Ann Arbor, Mich. ; also by 

 Mr. A. D. Hopkins, entomologist of the West Virginia Agricultural 

 Experiment Station, who reported the occurrence in Insect Life (Yol. 

 VII, p. 145), as follows: 



Quite a serious trouble, affecting different species of oak in and around Madison 

 [Wis.], was observed, wbich caused tbe death of isolated and groups of trees of 

 different ages. Upon examination, I found tbe larva of Agrilus hilineatus quite com- 

 mon in tbe bark of most of those that were just commencing to die. 1 also observed 

 wbat appeared to be tbis same trouble at different points through Ohio, Wisconsin 

 and Indiana ; and upon my return to West Virginia I noticed a number of trees dying 

 in the same manner ; one of which I examined, September 10, and found the larva 

 of the same Agrilus mining through the inner living bark and outer sapwood. 

 From what I have observed up to the present date with reference to the habits of 

 this insect, it is very evident to me that it is capable of attacking and killing healthy 

 oak and chestnut trees, and should the conditions at any time be especially favor- 

 able for its increase I anticipate that serious trouble will result from its attack. 



Of this species the same writer remarks in the Canadian Entomolo- 

 gist for October, 1896 (Vol. XXVIII, p. 246), that until the fall of 1895 

 " the dying of trees with which this insect was intimately associated 

 was decidedly on the increase." In the vicinity of the District of 

 Columbia, on the contrary, this condition has been constantly decreas- 

 ing for at least the last three years. 



THE SPECIES BRIEFLY DESCRIBED. 



For the identification of the beetle and its larva the accompanying 

 illustration (fig. 42) is presented. The beetle, shown at «, is elongate 

 and subcylindrical, like others of its genus. It is black, with a more 

 or less greenish tinge. The sides of thorax and elytra are clothed with 

 a light golden-yellow pubescence, and the elytra are each marked with a 

 stripe of the same color. An enlarged antenna is shown at the left (a), 

 and below are the claws of the hind feet of both sexes. The larva, 

 drawn to the same scale as the beetle, is illustrated at c. It is long, 

 slender, and considerably flattened. In color it is milk white or slightly 

 yellowish, except the mouth-parts and the peculiar anal fork, which are 

 dark brown. 



